Google: sys-kernel/lakitu-kernel-6_1: security update to 18244.85.5

medium Tenable Self-Hosted Container Security Plugin ID 450639

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

- In the Linux kernel, the following vulnerability has been resolved: mm/swap: fix race when skipping
swapcache When skipping swapcache for SWP_SYNCHRONOUS_IO, if two or more threads swapin the same entry at
the same time, they get different pages (A, B). Before one thread (T0) finishes the swapin and installs
page (A) to the PTE, another thread (T1) could finish swapin of page (B), swap_free the entry, then swap
out the possibly modified page reusing the same entry. It breaks the pte_same check in (T0) because PTE
value is unchanged, causing ABA problem. Thread (T0) will install a stalled page (A) into the PTE and
cause data corruption. One possible callstack is like this: CPU0 CPU1 ---- ---- do_swap_page()
do_swap_page() with same entry <direct swapin path> <direct swapin path> <alloc page A> <alloc page B>
swap_read_folio() <- read to page A swap_read_folio() <- read to page B <slow on later locks or interrupt>
<finished swapin first> ... set_pte_at() swap_free() <- entry is free <write to page B, now page A
stalled> <swap out page B to same swap entry> pte_same() <- Check pass, PTE seems unchanged, but page A is
stalled! swap_free() <- page B content lost! set_pte_at() <- staled page A installed! And besides, for
ZRAM, swap_free() allows the swap device to discard the entry content, so even if page (B) is not
modified, if swap_read_folio() on CPU0 happens later than swap_free() on CPU1, it may also cause data
loss. To fix this, reuse swapcache_prepare which will pin the swap entry using the cache flag, and allow
only one thread to swap it in, also prevent any parallel code from putting the entry in the cache. Release
the pin after PT unlocked. Racers just loop and wait since it's a rare and very short event. A
schedule_timeout_uninterruptible(1) call is added to avoid repeated page faults wasting too much CPU,
causing livelock or adding too much noise to perf statistics. A similar livelock issue was described in
commit 029c4628b2eb ("mm: swap: get rid of livelock in swapin readahead") Reproducer: This race issue can
be triggered easily using a well constructed reproducer and patched brd (with a delay in read path) [1]:
With latest 6.8 mainline, race caused data loss can be observed easily: $ gcc -g -lpthread test-thread-
swap-race.c && ./a.out Polulating 32MB of memory region... Keep swapping out... Starting round 0...
Spawning 65536 workers... 32746 workers spawned, wait for done... Round 0: Error on 0x5aa00, expected
32746, got 32743, 3 data loss! Round 0: Error on 0x395200, expected 32746, got 32743, 3 data loss! Round
0: Error on 0x3fd000, expected 32746, got 32737, 9 data loss! Round 0 Failed, 15 data loss! This
reproducer spawns multiple threads sharing the same memory region using a small swap device. Every two
threads updates mapped pages one by one in opposite direction trying to create a race, with one dedicated
thread keep swapping out the data out using madvise. The reproducer created a reproduce rate of about once
every 5 minutes, so the race should be totally possible in production. After this patch, I ran the
reproducer for over a few hundred rounds and no data loss observed. Performance overhead is minimal,
microbenchmark swapin 10G from 32G zram: Before: 10934698 us After: 11157121 us Cached: 13155355 us
(Dropping SWP_SYNCHRONOUS_IO flag) [[email protected]: v4] (CVE-2024-26759)

Solution

Update the sys-kernel/lakitu-kernel-6_1 library and its related packages to version 18244.85.5 or later.

Plugin Details

Severity: Medium

ID: 450639

Version: Revision 1.1

Type: Local

Family: Google COS Security Checks

Published: 10/1/2026

Updated: 10/1/2026

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.18

Vendor

Vendor Severity: MEDIUM

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2024-26759

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 3/23/2024

Reference Information

CVE: CVE-2024-26759

Detections

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